Calendar Spread

Calendars are net debit because the back-month option you buy is worth more than the front-month option you sell (more time = more value). The profit comes from the front-month decaying faster than the back-month, not from the initial credit. Think of the debit as paying for the time differential.

Calendar spreads use the SAME strike but DIFFERENT expirations (time spread). Vertical spreads use DIFFERENT strikes but the SAME expiration (price spread). Calendars profit from time decay differential; verticals profit from price movement to a target.

No. Maximum loss on a calendar spread is the net debit paid. This occurs if the stock moves far from the strike, making both options worthless (if OTM) or equally deep ITM (no spread value). Your risk is defined and limited.

At front-month expiration, the short option either expires worthless (if OTM) or needs to be closed/assigned (if ITM). The back-month option you own still has value. You can sell it to close the trade, or roll by selling a new front-month, creating another calendar.

At the strike, the front-month option has maximum time value decay (ATM options have highest theta). At the strike, the short option expires worthless while the long back-month retains significant value. Moving away from strike reduces this optimal scenario.

Roll if: (1) Stock is still near strike and thesis is intact, (2) Back-month still has significant time value, (3) Term structure remains favorable. Close entirely if: (1) Stock has moved far from strike, (2) Term structure has become unfavorable contango, (3) You need to redeploy capital.

Calendars are long vega. If IV rises across both months, back-month gains more than front-month (higher vega), creating profit. If IV falls, back-month loses more, creating loss. You can profit from IV increase even if stock is at strike, or lose from IV decrease at strike.

Common setup: Front-month 21-35 DTE, Back-month 50-75 DTE. This gives 30-45 days between expirations. Front-month is in accelerating theta decay; back-month has slower decay and higher vega. Avoid very short front-months (<14 DTE) - too much gamma risk.

Monitor as front-month goes ITM. Assignment is most likely when: (1) Deep ITM, (2) Near expiration, (3) Near ex-dividend date. If assigned on short call, you're short 100 shares but still own back-month call. Cover short shares and keep/sell the call, or exercise the call to cover.

Term structure determines the relative pricing of front vs back-month options. Backwardation (front IV > back IV) makes the front-month you're selling relatively more expensive - better entry. Contango (front IV < back IV) makes back-month expensive - worse entry. Even if you expect stable prices, term structure affects your cost and profit potential.

Enter calendars when term structure is in backwardation (front IV > back IV), expecting reversion to flat or contango. The term structure normalization provides 'carry' - profit from the front-month's excess IV dissipating. Track term structure percentile vs historical range. Enter below 30th percentile, exit above 70th.

Delta hedge with shares, not options. If calendar delta exceeds ±0.15, buy/sell shares to neutralize. Hedging with options would change the spread structure. Hedge only after position is profitable to protect gains. Size hedge based on current net delta, rebalance when delta moves ±0.10 from neutral.

Put skew is typically steeper (OTM puts more expensive) than call skew. This means put calendars at OTM strikes face more skew roll-down effect as the strike moves toward ATM. Call calendars at OTM strikes benefit from flatter skew. At ATM, skew effects are minimal. Choose based on skew shape at your target strike.

Include term structure data (not just price). Track IV for both months separately. Model bid-ask accurately (wider in back-month typically). Test multiple entry filters: term structure percentile, IV Rank, days between expirations. Calculate Sharpe ratio, not just win rate. Compare to alternative neutral strategies on same underlyings.

Calendars add long vega to offset short vega from condors, strangles, and butterflies. They reinforce positive theta (both strategies benefit from time decay). Use index calendars for market-wide vega hedge. Size based on portfolio vega - offset 30-50% of short vega exposure. Calendars 'diversify' your Greeks without adding directional risk.